add new mount

contrib/mount

@@ -57,6 +57,33 @@ def update_mount(buf, name, path):
 
     return ret.getvalue()
 
+RE_EOB = re.compile(
+    r'^(\s*\}\s*)$',
+    re.MULTILINE
+)
+def add_mount(buf, name, path):
+    ret = io.StringIO()
+    match = RE_EOB.search(buf)
+    if not match:
+        raise NotImplementedError('failed to add mount, no match for {!r} on \n\n\t{!r}'.format(
+            RE_EOB,
+            buf
+        ))
+    match_span = match.span()
+    match_groups = match.groups()
+
+    ret.write(buf[:match_span[0]])
+    ret.write('\t')
+    ret.write('"{}"'.format(name))
+    ret.write('\t')
+    ret.write('"{}"'.format(path))
+    ret.write('\n')
+    ret.write(match_groups[0])
+    ret.write(buf[match_span[1]:])
+
+    return ret.getvalue()
+
+
 
 def main_set_mount(argp):
     name, path = argp.set_mount
@@ -73,10 +100,11 @@ def main_set_mount(argp):
         mbuf = None
         if is_update:
             mbuf = update_mount(buf, name, path)
-            sanity = pyvmf.Cfg.loads(mbuf)
         else:  # is addative
             mbuf = add_mount(buf, name, path)
 
+        sanity = pyvmf.Cfg.loads(mbuf)
+
         fh.seek(0)
         nbytes = fh.write(mbuf)
         fh.truncate()